Two leading politicians in Montenegro have fallen victim to Russian pranksters who posed as the president and prime minister of Ukraine in telephone calls last week, officials in the Balkan country say.

Montenegrin Prime Minister Dusko Markovic and his predecessor, Milo Djukanovic, were tricked by Vladimir Krasnov and Aleksei Stolyarov, pranksters known as Vovan and Lexus, according to officials in the government and the ruling Democratic Party of Socialists.

They said the calls were a Russian provocation and part of a series of efforts by Moscow aimed at discrediting officials in Montenegro, whose successful bid to join NATO has angered Moscow.

The recorded conversations with the pranksters, who have fooled prominent people including Elton John in the past, were broadcast on Russian state TV. Their authenticity was confirmed by the government and the ruling party, which is chaired by Djukanovic.

Markovic's cabinet said he spoke to a prankster posing as Ukrainian President Petro Poroshenko for 17 minutes on May 24, the day before a NATO meeting at which Montenegro, which is to formally join the alliance in June, was welcomed as its newest member.

Montenegrin officials allege that Serbian and Russian nationalists plotted to take over parliament during October 2016 elections, assassinate then-Prime Minister Djukanovic, and install a pro-Russian leadership to keep the country out of NATO.